Addition of the release automation script

[frouioui]

This PR adds a script to automate the release process of the vitess operator.

The script can be used as follows:

OLD_VITESS_VERSION="13.0.0" NEW_VITESS_VERSION="14.0.3" NEW_OPERATOR_VERSION="2.7.4" NEXT_OPERATOR_VERSION="2.7.5" ./tools/release/do_release.sh          

[GuptaManan100]

In the release docs we should add that the PR created from this script should be normal merged and not squash-merged

[frouioui]

In the release docs we should add that the PR created from this script should be normal merged and not squash-merged

@GuptaManan100, I will do a second Pull Request. I plan to change the script a little bit once I have done it in OSS Vitess.